The present application relates to a fine particle measuring apparatus which optically measures a property of a fine particle such as a cell.
A flow cytometer is an apparatus which irradiates fine particles such as cells and beads which flow in a flow cell with light and detects fluorescence or scattering light emitted from the fine particles so as to optically measure a property of each of the fine particles.
In a case of detecting fluorescence of a cell, for example, cells which are marked by fluorescence coloring matters are irradiated with excitation light such as laser light which has appropriate wavelength and intensity. Then, fluorescence emitted from the fluorescence coloring matters is condensed by a lens or the like and light in an appropriate wavelength band is selected with a wavelength selecting element such as a filter and a dichroic mirror so as to detect the selected light with a light-receiving element such as a photo multiplier tube (PMT). At this time, fluorescence from a plurality of fluorescence coloring matters marked on cells can be simultaneously detected and analyzed by combining a plurality of wavelength selecting elements and light-receiving elements. Further, the number of fluorescence coloring matters which can be analyzed can be increased by combining excitation light of a plurality of wavelengths.
As a method for detecting fluorescence with a flow cytometer, there is a method for measuring intensities of light beams in continuous wavelength bands as a fluorescence spectrum as well as the method in which a plurality of light beams in discontinuous wavelength bands are selected with a wavelength selecting element such as a filter so as to measure intensities of the light beams in respective wavelength bands. A spectrum type flow cytometer which is capable of measuring a fluorescence spectrum divides fluorescence emitted from fine particles with a spectral element such as a prism and a grating. Then, the flow cytometer detects the divided fluorescence with a light-receiving element array in which a plurality of light-receiving elements of different detection wavelength bands are arranged. As the light-receiving element array, a PMT array or a photodiode array in which light-receiving elements which are PMTs or photodiodes are one-dimensionally arranged, or an array in which a plurality of independent detection channels such as two-dimensional light-receiving elements which are CCDs or CMOSs are arranged is used.
Japanese Unexamined Patent Application Publication No. 2003-83894 is an example of related art.